多孔氧化铝模板的制备及应用

以磷酸溶液为电解液、以高纯铝为阳极,采用两步阳极氧化法制备氧化铝模板。扫描电子显微镜(SEM)对其表面形貌分析表明,氧化铝膜为多孔结构,膜孔径随着阳极氧化电压的增大而不断增大。对阳极氧化电流密度变化分析证实,铝的阳极氧化经历了三个阶段:阻挡层的生成、多孔层的形成和多孔层的稳定生长。以制备的氧化铝膜为阴极、锌片为阳极,以硝酸锌和硼酸的混合液为电解液,采用交流电沉积方法制备了针状氧化锌纳米线。     

Co-氧化铝纳米阵列的结构与磁性研究

用二次阳极氧化法制备了多孔氧化铝膜，并以之为模板，用直流电沉积法成功地将Co金属组装入多孔氧化铝膜的纳米孔洞中，观察与测试了Co—氧化铝纳米阵列结构和磁性。结果发现，二次阳极氧化法在短时间内就能制备出较为有序的多孔氧化铝膜；Co—氧化铝纳米阵列中的Co金属纳米线有一定的结晶择优取向，并且当多孔氧化铝模板的孔径减小，择优取向发生优化；Co—氧化铝纳米阵列有明显的磁各向异性。     

多孔阳极氧化铝模板制备工艺的研究

以硫酸溶液为电解液,采用二次阳极氧化工艺制备高度有序的多孔阳极氧化铝模板.研究了电解液浓度、阳极氧化电压和阳极氧化温度对多孔阳极氧化铝模板形貌、孔径和孔间距的影响,并以高氯酸和丙酮的混合溶液为电解液,利用第三次阳极氧化,一步实现了多孔阳极氧化铝膜的通孔剥离,获得具有较大面积、韧性较好的通孔多孔阳极氧化铝模板.     

高度有序多孔氧化铝模板影响因素的研究

在酸性电解液中,用阳极氧化法制备得到了多孔阳极氧化铝(anodic aluminum oxide,AAO)模板。用金相显微镜观察了铝箔退火后表面上的晶界,并结合扫描电镜对多孔氧化铝薄膜进行了观察和表征。研究了影响多孔氧化铝模板孔洞有序性的关键性因素。实验结果表明,多孔阳极氧化铝膜的有序度依赖于铝箔预处理、氧化电压和电解液等的选择。     

氧化铝模板制备氮化碳纳米管

利用二次阳极氧化方法制备了高度有序的多孔氧化铝(AAO)模板,利用这些模板通过溶胶-凝胶过程和高温后处理制备了氮化碳纳米管。分别用SEM、XRD和XPS表征了AAO模板和氮化碳纳米管的形貌、物相结构以及表面元素组成,发现所制备的氮化碳纳米管彼此平行、表面光洁,而且氮化碳纳米管的直径与所用AAO模板的孔径基本一致。     

纳米孔阵列结构阳极氧化铝模板的应用研究现状

对铝基材实施阳极氧化处理,可在其表面形成氧化铝多孔膜。当氧化铝多孔膜的纳米孔排列成规则的阵列结构时,氧化铝多孔膜将具有许多其它纳米材料无法比拟的优势。综述了以具有规则纳米孔阵列结构的阳极氧化铝薄膜作为模板,通过复制、沉积、吸附等技术,制备具有各种特殊用途纳米材料的制备工艺,使用这些方法制备的纳米材料已经广泛地应用于催化、气体吸收、分离膜、微电子器件等。     

阳极氧化铝模板有序度影响因素的研究

在酸性电解液中,用阳极氧化法制备了多孔阳极氧化铝模板。用金相显微镜观察了铝箔退火前后的表面形貌,并结合扫描电镜对多孔氧化铝薄膜进行了形貌观察和表征。研究了影响多孔氧化铝模板孔有序性(分布均匀,大小一致)的关键性因素。实验结果表明,多孔阳极氧化铝膜结构特性依赖于铝箔预处理、氧化电压、电解液类型和温度等的选择。     

兰州大学成功制备出碳纳米管

日前,兰州大学在国内首次通过多孔氧化铝模板成功地在其孔内制备出高度取向的碳纳米管阵列结构。这标志着我国已在模板法制备碳纳米管这一前沿领域处于国际先进水平。 　　碳纳米管韧性很高,导电性极强,兼具金属性和半导体性,强度比钢高100倍,比重却只有钢的1／6。由于自由生长的碳纳米管取向杂乱,形态各异,同时又常有杂质伴生,难以提纯,严重制约了人们对碳纳米管物理、化学性质的研究和实际应用。现在国际上常采用多孔氧化硅模板,已成功实现了在其孔外取向生长碳纳米管阵列。 　　从1995年起,兰州大学利用电化学法制备出了多孔氧化铝模板,随后又运用这个模板成功地制备出了结构均匀、排列有序的碳纳米管阵列结构。而此次用多孔氧化铝模板制备出的这种高度取向的碳纳米管阵列结构,与采用多孔氧化硅模板制备的纳米管比较,工艺简便,成本较低,重复性好,可实现大面积生长,更为重要的是它非常有利于碳纳米管的基础研究和应用研究。 （摘编）     

模板法交流电沉积铜纳米线阵列及其表征

先通过二次阳极氧化法制备多孔阳极氧化铝膜模板,再采用交流电沉积法将Cu金属填入模板的纳米孔洞中得到铜纳米线阵列。分别采用扫描电镜、透射电镜和X射线衍射仪对Cu纳米线阵列的形貌和晶体结构进行表征。结果表明,多孔氧化铝模板的孔洞排布致密、均匀而有序。交流电沉积所得Cu纳米线为单晶结构,直径为60~90 nm,长度为0.5~4.0μm。     

纳米有序多孔阳极氧化铝制备方法的研究进展

多孔阳极氧化铝(PAA)模板以六角形元胞紧密排列,孔径大小可调,且化学稳定性好,近年来在催化、传感、过滤和仿生等领域受到了越来越多的关注。PAA模板的制备一直以来都是研究的热点,因为模板的结构和性质直接影响其应用的效果。本文在简要介绍了自组织有序多孔阳极氧化铝的特点及影响因素的基础上,较为全面地综述了制备自组织PAA模板不同方法的研究进展,包括温和阳极氧化法、强烈阳极氧化法、脉冲式阳极氧化法和周期性阳极氧化法。具体分析了不同阳极氧化方法的特点以及各自得到的氧化铝模板不同的特点和应用范围,说明了氧化电压、氧化温度和电解液种类在制备PAA模板时对其孔洞尺寸的重要作用,最后对阳极氧化铝膜的发展前景进行了展望。     

Synthesis of NiO-embedded carbon nanotubes using corona discharge enhanced chemical vapor deposition

Large-scale synthesis of NiO-embedded carbon nanotubes (CNTs) has been achieved using a nanoporous anodic aluminum (AAO) membrane as a template, with the aid of CH₄/H₂ corona discharge enhanced chemical vapor deposition (CVD). NiO nanoparticles are first introduced into the nanopores of the alumina template through wet impregnation method. The loading of NiO nanoparticles into the CNTs and the synthesis of the CNTs were simultaneously performed in the corona discharge reactor. Transmission electron microscopy characterization showed that the NiO nanoparticles are encapsulated into the walls of the CNTs, but not present on the outer surfaces.     

Confined conversion of CuS nanowires to CuO nanotubes by annealing-induced diffusion in nanochannels

Copper oxide (CuO) nanotubes were successfully converted from CuS nanowires embedded in anodic aluminum oxide (AAO) template by annealing-induced diffusion in a confined tube-type space. The spreading of CuO and formation of CuO layer on the nanochannel surface of AAO, and the confinement offered by AAO nanochannels play a key role in the formation of CuO nanotubes.     

Fabrication and electrochemical properties of carbon nanotube array electrode for supercapacitors

The multiwalled carbon nanotube (MWNT) array was fabricated by chemical vapor deposition (CVD) in the template of porous alumina from the carbonaceous source of C₂H₂ in the presence of a catalyst of ferric metals. To utilize the external surface other than the inner surface of the carbon nanotubes, 1 mol/L sulfuric acid was applied to remove off the most part of AAO template on the carbon nanotube electrode. The electrochemical performances of the carbon nanotube array electrode were investigated by use of the cyclic voltammetry, galvanostatic charge/discharge and ac impedance methods for its application in supercapacitors. The specific capacitance of 365 F/g of the electrode was achieved with the discharge current density of 210 mA/g in the solution of 1 mol/L H₂SO₄. In addition, the carbon nanotube array electrode was found to have low equivalent series resistance (ESR) and good cycling stability.     

Selective growth of palladium and titanium dioxide nanostructures inside carbon nanotube membranes

ABSTRACT: Hybrid nanostructured arrays based on carbon nanotubes (CNT) and palladium or titanium dioxide materials have been synthesized using self-supported and silicon-supported anodized aluminum oxide (AAO) as nanoporous template. It is well demonstrated that carbon nanotubes can be grown using these membranes and hydrocarbon precursors that decompose at temperatures closer to 600°C without the use of a metal catalyst. In this process, carbonic fragments condensate to form stacked graphitic sheets, which adopt the shape of the pores, yielding from these moulds' multi-walled carbon nanotubes. After this process, the ends of the tubes remain open and accessible to other substances, whereas the outer walls are protected by the alumina. Taking advantage of this fact, we have performed the synthesis of palladium and titanium dioxide nanostructures selectively inside carbon nanotubes using these CNT-AAO membranes as nanoreactors.     

Carbon nanotube–nanopipe composite vertical arrays for enhanced electrochemical capacitance

The newly-designed vertical array structure of carbon nanotubes (CNTs) surrounding carbon nanopipes (CNTs@CNPs) was fabricated, which includes the formation of the primary CNP (ca. 200 nm in diameter) arrays in virtue of the anodic aluminum oxide (AAO) membrane template with infiltration of polymer solution containing metal catalyst precursor, followed by carbonization and CVD growth of the secondary CNTs (20 nm in diameter). The secondary CNTs with controllable density/length are grown both inside and outside the primary CNPs, which not only induce the four times increase of the specific surface areas for the samples, but also largely enhance the interconnection between the vertical CNPs for good electric conductance. The unique CNTs@CNPs arrays significantly improve the electrochemical capacitance per unit area with great long-term stability, indicating the promise as new material platform for development of advanced energy-storage devices.     

Copper-assisted,templated preparation of submicron-sized tubular CNT arrays by corona discharge enhanced CVD

The corona discharge enhanced CVD technique is used to synthesize copper nanoparticle-doped submicron carbon nanotubes. The average diameter of prepared copper nanoparticles is as small as 3 nm. Under the blank membrane condition (no metal loading), however, no nanotubes are formed. The existence of copper nanoparticles seems to facilitate the homogeneous deposition of carbon species onto the interior surface of an AAO membrane.     

Mechanistic study of cobalt catalyzed growth of carbon nanofibers in a confined space by plasma-assisted chemical vapor deposition

Carbon nanofibers (CNFs) were grown in the porous anodic aluminum oxide (AAO) thin film grown on the Si wafer by electron cyclotron resonance chemical vapor deposition using cobalt as the catalyst. A larger Co particle electrodeposited in the AAO pore channel produced vertically aligned CNFs with a tube diameter in compliance with the pore size of the AAO template. On the other hand, a smaller Co particle resulted in CNF growth with a nonuniform distribution of the tube diameter and a sparse tube density. Amorphous carbon residue produced under the plasma-assisted CNF growth condition seemed to play an essential role leading to the observation. A growth mechanism is proposed to delineate the volume effect of the electrodeposited Co catalyst on the CNF growth confined in pore channels of the AAO template.     

Carbon nanotubes based on anodic aluminum oxide nano-template

The effect of reaction gas and catalyst on the growth of carbon nanotubes (CNTs) in the anodic aluminum oxide (AAO) nano-template was investigated. A mechanism of CNT growth was proposed, which involves the competitive catalytic carbon deposition between on the Co catalyst particles electrodeposited at the bottom of the pores and on the AAO template itself. Presence of H₂ in the reacting gas mixture significantly affected the morphology and the wall structure of synthesized CNTs: CNTs of high crystallinity grew out of pores with H₂ while no CNTs overgrew in the absence of H₂. CNT synthesis by CO disproportionation showed a lower growth rate and a higher degree of ordering than those grown by C₂H₂ pyrolysis. The unified mechanism of CNT growth on AAO template is also proposed.     

Growth of mechanically fixed and isolated vertically aligned carbon nanotubes and nanofibers by DC plasma-enhanced hot filament chemical vapor deposition

Vertically aligned, mechanically isolated, multiwalled carbon nanotubes (MWCNTs) and nanofibers (MWCNFs) were grown using an array of catalyst nickel nanowires embedded in an anodic aluminum oxide (AAO) nanopore template using DC plasma-enhanced hot filament chemical vapor deposition (HFCVD). The nickel nanowire array, prepared by electrodeposition of nickel into the pores of a commercially available AAO membrane, acts as a template for CNT and CNF growth. It also provides both a mechanical “fixed support” boundary condition and enforces sufficient spatial separation of the CNT/CNFs from each other to enable reliable and well-controlled mechanical testing of individual vertically aligned CNT/CNFs. In contrast with other AAO-templated growth methods, no post-growth etching of the AAO is required, since the CNTs/CNFs grow out of the pores and remain vertically aligned. A mixture of hydrogen and methane was used for the growth, with hydrogen acting as a dilution and source gas for the DC plasma, and methane as the carbon source. A negative bias was applied to the sample mount to generate the DC plasma. The filaments provided the necessary heat for dissociation of molecular species, and also heat the sample itself significantly. Both of these effects assist the CNT/CNF growth. Minimal heating came from the low-power plasma. However, the associated DC field was essential for the vertical alignment of the CNTs and CNFs. Scanning electron, transmission electron, and atomic force microscopy confirm that the CNT/CNFs are composed of graphitic layers, and form a vertically aligned, relatively uniform, and dense array across the AAO template. A significant number of the structures grown are indeed high quality nanotubes, as opposed to more defective nanofibers that are often predominant in other growth methods. This method has the advantage of being scalable and consuming less power than other techniques that grow vertically aligned CNTs/CNFs.     

Theoretical Computational Fluid Dynamics Study of the Chemical Vapor Deposition Process for the Manufacturing of a Highly Porous 3D Carbon Foam

Aerographite is a three‐dimensional carbon foam with a tetrapodal morphology. The manufacturing of aerographite is carried out in a chemical vapor deposition (CVD) process, based on a zinc oxide (ZnO) template, in which the morphology is replicated into a hollow carbon shell. During the replication process, the template is reduced by the simultaneous formation of the carbon structure. The CVD process is one of the most efficient methods for the manufacturing of various carbon nanostructures, such as graphene or carbon nanotubes (CNTs). Based on the growth mechanism of aerographite, a computational fluid dynamics model is presented for the fundamental investigations of the temperature and flow/microflow behavior during the replication process. This allows a deeper process understanding and further optimizations.